Display control device and display control method of synchronizing images under panel self-refresh
Provided is a display control device that can, even with a self-emitting display, minimize power consumption and dramatically increase the battery life time of information device. The display control device includes: a phase adjustment circuit that adjusts a phase difference between input image data including a vertical blanking period and memory image data read from a frame buffer, by adjusting the number of vertical blanking lines on the basis of a difference between the number of vertical lines related to the input image data and the number of vertical lines related to phase adjusted image data in which the number of vertical blanking lines related to the memory image data is adjusted, and generating the phase adjusted image data; a selector that outputs the phase adjusted image data to the display as output image data in the period lasting until image display under PSR terminates; and a vertical line number calculation circuit that outputs a vertical line number signal related to the number of vertical lines related to output image data to the display until when a head of a frame of the output image data is output.
1. A display control device for controlling image display on a display, comprising:
a phase adjustment circuit that adjusts a phase difference between input image data including a vertical blanking period supplied from a predetermined transmission device and memory image data read from a frame buffer for panel self-refresh (PSR), by adjusting a number of vertical blanking lines related to the memory image data based on a difference between a number of vertical blanking lines related to the input image data and a number of vertical blanking lines related to phase adjusted image data in which the number of vertical blanking lines related to the memory image data is adjusted, and generating the phase adjusted image data;
a multiplexer that selects any one of the input image data, the memory image data, and the phase adjusted image data and outputs the selected data to the display as output image data; and
a vertical line number calculation circuit that calculates a number of vertical blanking lines related to the output image data and outputs a vertical line number signal related to the calculated number of vertical blanking lines related to the output image data to the display until a head of a frame of the output image data is output to the display,
wherein the multiplexer selects the phase adjusted image data during a period before image display under PSR on the display terminates, after a lapse of a predetermined period.
2. The display control device according to claim 1 , wherein
the phase adjustment circuit calculates an amount of increase/decrease in the number of vertical blanking lines related to the memory image data, and generates a vertical blanking line number increment/decrement signal related to the amount of increase/decrease, and
the vertical line number calculation circuit calculates a number of vertical blanking lines related to the output image data based on a vertical blanking line number increment/decrement signal.
3. The display control device according to claim 2 , wherein
the vertical line number calculation circuit comprises:
a calculation circuit that calculates the number of vertical blanking lines related to the phase adjusted image data in accordance with the vertical blanking line number increment/decrement signal; and
an update circuit that updates the number of vertical blanking lines related to the output image data reflecting a previous output image data based on the number of vertical blanking lines related to the phase adjusted image data calculated by the calculation circuit and outputs the number of vertical blanking lines related to the output image data.
4. The display control device according to claim 2 , wherein
the phase adjustment circuit comprises:
a line difference calculation circuit that determines a difference between the number of vertical blanking lines related to the input image data and the number of vertical blanking lines related to the phase adjusted image data;
an increment/decrement amount determination circuit that generates the vertical blanking line number increment/decrement signal based on the difference determined by the line difference calculation circuit; and
an increment/decrement circuit that increases or decreases the number of vertical blanking lines related to the memory image data in accordance with the vertical blanking line number increment/decrement signal and generates the phase adjusted image data.
5. The display control device according to claim 1 , further comprising
a PSR control circuit that generates a phase adjustment signal when control information supplied from the transmission device includes information indicating that image display under PSR on the display terminates, after a lapse of the predetermined period, wherein
upon reception of the phase adjustment signal, the phase adjustment circuit generates the phase adjusted image data and generates a selection signal causing the multiplexer to select the phase adjusted image data.
6. An image display system comprising:
the display control device according to claim 1 ;
a transmission device that outputs the input image data to the display control device; and
a frame buffer for PSR.
7. A display control device for controlling image display on a display, comprising:
an adjustment calculation circuit that, in a predetermined period subsequent to a panel self-refresh (PSR) period, adjusts a phase difference between input image data including a vertical blanking period supplied from a predetermined transmission device just after the PSR period and image data read from a frame buffer for PSR, by calculating an amount of increase/decrease in a number of vertical blanking lines related to the image data based on a difference between a number of vertical blanking lines related to the input image data and a number of vertical blanking lines related to adjusted image data in which the number of vertical blanking lines related to the image data is adjusted, and generating a vertical blanking line number increment/decrement signal related to the calculated amount of increase/decrease;
an adjusted image generator circuit that generates the adjusted image data by adjusting the number of vertical blanking lines related to the image data based on a vertical blanking line number increment/decrement signal; and
a multiplexer that selects at least one of the input image data and the adjusted image data and outputs the selected data to the display as output image data,
wherein the adjustment calculation circuit further calculates a number of vertical blanking lines related to the output image data and outputs a vertical line number signal related to the calculated number of vertical blanking lines related to the output image data to the display until a head of a frame of the output image data is output to the display.
8. The display control device according to claim 7 , wherein the multiplexer selects the adjusted image data during a period before image display under PSR on the display terminates, after a lapse of the predetermined period.
9. An image display system comprising:
the display control device according to claim 7 ;
a transmission device that outputs the input image data to the display control device; and
a frame buffer for PSR.
10. The display control device according to claim 7 , wherein the amount of increase/decrease in the number of vertical blanking lines is less than or equal to a predetermined threshold during the predetermined period.
11. A display control method for controlling image display on a display in a display control device, comprising:
adjusting a phase difference between input image data including a vertical blanking period supplied from a predetermined transmission device and memory image data read from a frame buffer for panel self-refresh (PSR), by adjusting a number of vertical blanking lines related to the memory image data based on a difference between a number of vertical blanking lines related to the input image data and a number of vertical blanking lines related to phase adjusted image data in which the number of vertical blanking lines related to the memory image data is adjusted, and generating the phase adjusted image data;
selecting any one of the input image data, the memory image data, and the phase adjusted image data and outputting the selected data to the display as output image data; and
calculating a number of vertical blanking lines related to the output image data and outputting a vertical line number signal related to the calculated number of vertical blanking lines related to the output image data to the display until a head of a frame of the output image data is output to the display, wherein
the phase adjusted image data is selected during a period before image display under PSR on the display terminates, after a lapse of a predetermined period.
12. The display control method according to claim 11 , wherein
the step of generating the phase adjusted image data comprises calculating an amount of increase/decrease in the number of vertical blanking lines related to the memory image data, and generating a vertical blanking line number increment/decrement signal related to the calculated amount of increase/decrease, and
the step of calculating the number of vertical blanking lines comprises calculating the number of vertical blanking lines related to the output image based on a vertical blanking line number increment/decrement signal.
13. The display control method according to claim 12 , wherein
the step of generating the phase adjusted image data further comprises:
determining a difference between the number of vertical blanking lines related to the input image data and the number of vertical blanking lines related to the phase adjusted image data;
generating the vertical blanking line number increment/decrement signal based on the difference; and
increasing or decreasing the number of vertical blanking lines related to the memory image data in accordance with the vertical blanking line number increment/decrement signal and generating the phase adjusted image data.
14. The display control method according to claim 11 , wherein
the step of calculating the number of vertical blanking lines further comprises:
calculating the number of vertical blanking lines related to the phase adjusted image data in accordance with the vertical blanking line number increment/decrement signal; and
updating the number of vertical blanking lines related to a previous output image data based on the number of vertical blanking lines related to the phase adjusted image data and outputting the number of vertical blanking lines related to the output image data.
15. The display control method according to claim 11 , wherein
the method further comprises the step of generating a phase adjustment signal when control information supplied from the transmission device includes information indicating that image display under PSR on the display terminates after a lapse of the predetermined period, and
the step of generating the phase adjusted image data further comprises, upon reception of the phase adjustment signal, generating the phase adjusted image data and generating a selection signal causing selection of the phase adjusted image data.
16. A display control method for controlling image display on a display in a display control device, comprising:
adjusting a phase difference between input image data including a vertical blanking period supplied from a predetermined transmission device and image data read from a frame buffer for panel self-refresh (PSR), in a predetermined period subsequent to a PSR period, by calculating an amount of increase/decrease in a number of vertical blanking lines related to the image data based on a difference between a number of vertical blanking lines related to the input image data and a number of vertical blanking lines related to adjusted image data in which the number of vertical blanking lines related to the image data is adjusted, and generating a vertical blanking line number increment/decrement signal related to the amount of increase/decrease;
generating the adjusted image data by adjusting the number of vertical blanking lines related to the image data based on a vertical blanking line number increment/decrement signal;
selecting at least one of the input image data and the adjusted image data and outputting selected data to the display as output image data;
calculating a number of vertical blanking lines related to the output image data; and
outputting a vertical line number signal related to the calculated number of vertical blanking lines related to the output image data to the display until a head of a frame of the output image data is output to the display.
17. The display control method according to claim 16 , wherein the adjusted image data is selected during a period before image display under PSR on the display terminates, after a lapse of the predetermined period.